Move CrTrackingArea from chrome/browser/ui/cocoa to ui/base/cocoa.

chrome/browser/ui/cocoa/tracking_area.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef CHROME_BROWSER_UI_COCOA_TRACKING_AREA_H_
-#define CHROME_BROWSER_UI_COCOA_TRACKING_AREA_H_
-
-#import <AppKit/AppKit.h>
-
-#include "base/memory/scoped_nsobject.h"
-
-@class CrTrackingAreaOwnerProxy;
-
-// The CrTrackingArea can be used in place of an NSTrackingArea to shut off
-// messaging to the |owner| at a specific point in time.
-@interface CrTrackingArea : NSTrackingArea {
- @private
-  scoped_nsobject<CrTrackingAreaOwnerProxy> ownerProxy_;
-}
-
-// Designated initializer. Forwards all arguments to the superclass, but wraps
-// |owner| in a proxy object.
-- (id)initWithRect:(NSRect)rect
-           options:(NSTrackingAreaOptions)options
-             owner:(id)owner
-          userInfo:(NSDictionary*)userInfo;
-
-// Prevents any future messages from being delivered to the |owner|.
-- (void)clearOwner;
-
-// Watches |window| for its NSWindowWillCloseNotification and calls
-// |-clearOwner| when the notification is observed.
-- (void)clearOwnerWhenWindowWillClose:(NSWindow*)window;
-
-@end
-
-// Scoper //////////////////////////////////////////////////////////////////////
-
-// Use an instance of this class to call |-clearOwner| on the |tracking_area_|
-// when this goes out of scope.
-class ScopedCrTrackingArea {
- public:
-  // Takes ownership of |tracking_area| without retaining it.
-  explicit ScopedCrTrackingArea(CrTrackingArea* tracking_area = nil);
-  ~ScopedCrTrackingArea();
-
-  // This will call |scoped_nsobject<>::reset()| to take ownership of the new
-  // tracking area.  Note that -clearOwner is NOT called on the existing
-  // tracking area.
-  void reset(CrTrackingArea* tracking_area = nil);
-
-  CrTrackingArea* get() const;
-
- private:
-  scoped_nsobject<CrTrackingArea> tracking_area_;
-  DISALLOW_COPY_AND_ASSIGN(ScopedCrTrackingArea);
-};
-
-#endif  // CHROME_BROWSER_UI_COCOA_TRACKING_AREA_H_